Description : A hardened steel essentially contains (A) Sorbite (B) Troostite (C) Martensite (D) None of these
Last Answer : (C) Martensite
Description : Explain the formation of micro structures of pearlite, bainite and martensite in steel.
Last Answer : If austenite containing about 0.80 percent carbon is slowly cooled through the critical temperature, ferrite and cementite are rejected simultaneously, forming alternate plates or lamellae. This ... This phase has a tetragonal crystal structure and contains carbon in supersaturated solid solution.
Description : Cold cracking in the heat affected zone of a high strength steel weld can take place because of the (A) Retained austenite (B) Martensite formation (C) Relatively high sulphur content in the base metal (D) Sufficient hydrogen present in the welding arc
Last Answer : (B) Martensite formation
Description : Sub zero treatment of steel is done to (A) Suppress martensite transformation (B) Enhance its working performance in sub zero atmosphere (C) Reduce the retained austenite in hardened steel (D) Induce temper brittleness after its hardening
Last Answer : Option C
Description : Transformation range for ferrous material is the temperature interval during which __________ is formed during its heating. (A) Cementite (B) Austenite (C) Martensite (D) Pearlite
Last Answer : Option B
Description : Maraging steels derive their strength from the following mechanism: (A) A fine, highly dislocated and strong martensite (B) Fine dispersions of inter-metallic of Fe, Ni, Ti etc (C) Fine ... alloy carbides in a ferrite matrix (D) Fine dispersions of Fe3 C nucleated on dislocations in austenite
Last Answer : Option A
Description : Maximum change in the hardness of martensite occurs in the carbon content range of __________ percent in steel. (A) 0.01 to 0.10 (B) 0.2 to 0.4 (C) 0.5 to 0.7 (D) 0.8 to 1.0
Last Answer : (B) 0.2 to 0.4
Description : Eutectoid composition of carbon steel at room temperature is (A) Cementite (B) Pearlite (C) Martensite (D) Ferrite
Description : __________ of austenite decreases the hardenability in steel. (A) Fine grains (B) Coarse grains (C) Homogeneity (D) Dissolved elements (except cobalt)
Last Answer : (D) Dissolved elements (except cobalt)
Description : ________ is not a heat treatment process. (A) Cyaniding (B) Parkerizing (C) Austempering (D) Martempering
Last Answer : (B) Parkerizing
Description : Austempering process results in the formation of __________ structure. (A) Martensitic (B) Bainitic (C) Carburised (D) Stressed
Description : A steel rod of sectional area 250 sq. mm connects two parallel walls 5 m apart. The nuts at the ends were tightened when the rod was heated to 100°C. If steel = 0.000012/C°, Esteel = 0.2 MN/mm2 , the ... N/mm2 (B) 100 N/mm2 (C) 120 N/mm2 (D) 150 N/mm2 Answer: Option
Last Answer : (C) 120 N/mm
Description : __________ is the process of coating the surface of steel with aluminium oxide, thereby imparting it increased resistance to corrosion & oxidation upto a temperature of 700°C. (A) Veneering (B) Galvanising (C) Electroplating (D) Calorising
Last Answer : (D) Calorising
Description : Steels with high carbon equivalent have poor Weldability, because in these steels during welding (A) Carbon and other alloying elements get oxidised from the weld pool (B) Excessive ferrite forms in the ... of carbon and other element occurs in the weld pool leading to poor properties of the weld
Last Answer : (C) Martensite forms in the heat affected zone leading to poor toughness/ductility of the weld
Description : What could be a possible cause for sudden foaming in a cooling tower?
Last Answer : Assuming that no other changes have been made, especially to the water treatment chemicals, the most common outcome to this mystery is a leaking heat exchanger. Begin a systematic check of all of ... in the tower. In addition, not all of these components will set off a conductivity alarm
Description : Which of the following is the hardest? (A) Cementite (B) Pearlite (C) Austenite (D) Ferrite
Last Answer : (C) Austenite
Description : Secondary hardening in steels arises out of the (A) Precipitation of fine alloy carbides at high temperatures (B) Refinement of ferrite grain size by working (C) Decomposition of retained austenite upon heat treatment (D) Precipitation of complex inter-metallic upon heat treatment
Description : Which of the following processes is followed by unsaturated air (with dry bulb temperature 12°C and relative humidity 47%) passing through water spray washer (temperature of water being constant at 40°C ... (B) Heating only (C) Both heating and humidification (D) Evaporative cooling
Last Answer : (C) Both heating and humidification
Description : Which of the following psychrometric processes is followed by water vapour laden unsaturated air, when it is passed through solid or liquid adsorbent? (A) Cooling and dehumidification ... (C) Dehumidification with dry bulb temperature remaining constant (D) None of these
Last Answer : (B) Heating and dehumidification at almost constant wet bulb temperature
Description : Pick out the wrong statement. (A) Pasteurisation of milk involves moderate heating followed by cooling (B) Bakeries and breweries make use of yeasts (C) Enzyme is a complex nitrogenous compound (D) Oils and fats are alkaloids
Last Answer : (D) Oils and fats are alkaloids
Description : A first order reaction requires two unequal sized CSTR. Which of thefollowing gives higher yield? (A) Large reactor followed by smaller one (B) Smaller reactor followed by larger one (C) Either of the arrangement (A) or (B) will give the same yield (D) Data insufficient, can't be predicted
Last Answer : (C) Either of the arrangement (A) or (B) will give the same yield
Description : A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case, (A) The cooling rate will be the same for the two spheres and hence the ... equal amount of radiation from the surrounding in the beginning (D) Both (B) & (C)
Last Answer : (D) Both (B) & (C)
Description : In a gas-liquid shell and tube heat exchanger, the (A) Presence of a non-condensable gas decreases the condensing film coefficient (B) Gases under high pressure are routed through the tube side, because high pressure ... water or steam condensate remain localised to the tubes (D) All 'a', 'b' & 'c'
Last Answer : (D) All 'a', 'b' & 'c'
Description : The preferred reacting system for oxidation of o-xylene to phthalic anhydride is (A) Jacketed liquid phase CSTR (B) Jacketed steam heated multitubular reactor (C) Multitubular reactor with cooling (D) Multistage multitubular reactor with interstage cooling
Last Answer : (A) Jacketed liquid phase CSTR
Description : In a refrigerator what produces the cooling? (1) The ice which deposits on the freezer (2) The sudden expansion of a compressed gas (3) The evaporation of a volatile liquid (4) None of these
Last Answer : (4) None of these Explanation: Basically, refrigeration system consists of devices that compress and expand refrigerant gas. When refrigerant gas is compressed it expels heat and when it is suddenly ... inside of the fridge is cooled to a temperature below the ambient temperature of the room.
Description : In a refrigerator what produces the cooling ? (1) The ice which deposits on the freezer (2) The sudden expansion of a compressed gas (3) The evaporation of a volatile liquid (4) None of these
Last Answer : None of these
Description : What is austenite ?
Last Answer : solid solution of gamma iron ( FCC) in a solid solution of iron and carbon at temperatures above 729 ° C and between 1492 C is called austenite.
Description : What is the difference between austenite stabilisers and ferrite stabilisers ?
Last Answer : Austenite stabilisers have the effect of extending the temperature range overwhich austenite is formed. Such elements are carbon, manganese, nickel, copper and cobalt. Ferrite stabilisers have the ... is formed. Such elements are silicon, chromium, molybdenum, tungsten, titanium and niobium.
Description : Explain the difference between ferrite, austenite and graphite ?
Last Answer : Ferrite is the solid solution of carbon and other constituents in alpha-iron. It is soft, ductile and relatively weak. Austenite is the solid solution of carbon and other constituents in ... is also found at ordinary temperatures in some stainless steels. Graphite has a hexagonal layer lattice.
Description : Regeneration of molecular sieve requires it to be heated to a temperature of about __________ °C. (A) 80-120 (B) 200-300 (C) 600-800 (D) 1000-1100
Last Answer : (D) 1000-1100
Description : In your study of the fossil record of early mammals, you notice a changing environment is followed by the initial appearance of a tree-climbing species, which is then followed by many later tree-climbing ... is an example of A) anagenesis. B) gradualism. C) species selection. D) adaptive radiation.
Last Answer : D) adaptive radiation.
Description : Recall homework 2 in which we calculated emissivity for a single layer atmosphere. If the atmosphere were to suddenly become a perfect emitter (i.e., if e = 1 rather than e = 0.8), ... . (d) There would be initial warming followed by cooling as the planet moves toward radiative equilibrium.
Last Answer : (c) The surface temperature would be higher.
Description : The induced voltage across a coil with 250 turns that is located in a magnetic field and is changing at a rate of 8 Wb/s is A. 1,000 V B. 2,000 V C.31.25 V D. 3,125 V
Last Answer : The induced voltage across a coil with 250 turns that is located in a magnetic field and is changing at a rate of 8 Wb/s is 2,000 V
Description : A circular plate, a cube and a sphere, all made up of same material and having the same mass, are heated to 300°C and left in a room. Which of them will have the slowest rate of cooling? (1) Circular plate (2) Cube (3) Sphere (4) All will cool at the same rate
Last Answer : (3) Sphere Explanation: In the late of 17th century British scientist Isaac Newton studied cooling of bodies. Experiments showed that the cooling rate is approximately proportional to the difference of temperatures between the heated body and the environment.
Description : A __________ is a type of heat exchange system where water is heated to its' boiling point via combustion of a fuel blown through a tube submerged in water. a. Condensate loop b. Hyperbolic cooling tower c. Steam boiler d. All of above
Last Answer : c. Steam boiler
Last Answer : Sphere
Description : The operation of a transistor requires ______ (a) Emitter is heated (b) base is heated (c) collector be heated (d) none of above
Last Answer : (d) none of above
Description : A machine requires an effort of 10 kg to lift a load of 250 kg and an effort of 13 kg for a load of 400 kg. The effort required to lift a load of 500 kg will be a.25 kg b.107 dynes c.15 kg d.35 kg e.45 kg
Last Answer : c. 15 kg
Description : An adult patient with a history of bacterial endocarditis requires prophylactic administration of antibiotics prior to removal of teeth. Indicate the pre-operative regimen:** A. Amoxicillin 2 gram ... orally six hours before operation C. Tetracycline 250-500 mg orally 2 hours before treatment
Last Answer : A. Amoxicillin 2 gram one hour before operation orally
Description : A dynamic RAM has refresh cycle of 32 times per msec. Each refresh operation requires 100 nsec and a memory cycle requires 250 nsec. What percentage of memory’s total operating time is required for refreshes? (A) 0.64 (B) 0.96 (C) 2.00 (D) 0.32
Last Answer : Answer: D Explanation: in 1ms : refresh = 32 times Memory cycle = 1ms/250ns = 106ns/250ns = 4000 times Therefore, % of refresh time = (32 x 100ns)/(4000 x 250ns) = 3200ns/1000000 x 100% = 0.32%
Description : Addition of plasticisers to polymers results in partial neutralisation of intermolecular forces of attraction between the macro-molecules thereby increasing its (A) Tensile strength (B) Chemical resistance (C) Flexibility (D) All (A), (B) & (C)
Last Answer : (C) Flexibility
Description : Crude oil is subjected to vacuum distillation in the last stage, because (A) High boiling point products like heavy fuel oil & lubricating oils are heat sensitive and may decompose (B) Lighter/low ... prone to thermal decomposition (C) High purity products can be obtained thereby (D) None of these
Last Answer : (A) High boiling point products like heavy fuel oil & lubricating oils are heat sensitive and may decompose
Description : Which of the following grinding mills has the horizontally arranged rods as the grinding elements thereby delivering more uniform granular products with minimum fines? (A) Compartment mill (B) Rod mill (C) Pebble mill (D) Tube mill
Last Answer : (B) Rod mill
Description : Lead pipes are not safe for carrying drinking water because water containing dissolved oxygen attacks lead thereby forming poisonous Pb (OH)2 . Lead pipes are readily corroded by (A) Dilute HCI (B) Acetic acid (C) Concentrated H2SO4 (D) None of these
Last Answer : (B) Acetic acid
Description : Lead pipes are not safe for carrying drinking water, because water, containing dissolved oxygen attacks lead thereby forming poisonous Pb(OH)2 . Lead pipes are readily corroded by (A) Dilute HCl (B) Acetic acid (C) Concentrated H2SO4 (D) None of these
Description : A coal with high ash content is undesirable, as (A) It is abrasive to the coal pulveriser (i.e. ball mill) and the combustion chamber (B) The ash in molten condition gets absorbed in the pores of the ... and stick to the boiler tubes thereby reducing the heat transfer (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pitch creosote mixture (PCM) as compared to furnace oil is a better fuel, because its (A) Emissivity factor is higher (B) Sulphur content is lower (C) Flue gas has lower dew point thereby facilitating more waste heat recovery (D) All (A), (B) and (C)
Description : Pick out the wrong statement. (A) Loamy soil is the best soil for vigorous plant growth, while the clayey soil is solid and hence the plant roots penetrate with difficulty (B) Large ... vegetables (D) Cereal crops grown on alkaline soil absorb higher amount of fluorides thereby spreading fluorosis
Last Answer : (C) Application of large excess of Potassic fertiliser in soil increases the valuable carotene in fruits and vegetables
Description : The widest explosive limit is of __________, thereby making it the most explosive gas. (A) Acetylene (B) Petrol vapor (C) Hydrogen (D) Carbon monoxide
Last Answer : (A) Acetylene
Description : Pick out the wrong statement pertaining to 'green house' for the plants. (A) 'Green house' (made of glass) allows visible sunlight (i.e., short wavelength solar radiation like ultra-violet rays) ... ' thereby warming up the earth's surface (D) 'Green house' is colder than the outside atmosphere
Last Answer : (D) 'Green house' is colder than the outside atmosphere